Coaxial step attenuator



Filed Aug. 31, 1964 17, 1967 M. CONNEY 3,299,373

COAXIAL STEP ATTENUATOH 2 Sheets-$heet 2 INVENTOR. M/MCZZLUJ :oAm ry BY Wm M ATTOIF/Vfy United States Patent 3,299,373 COAXIAL STEP ATTENUATQR Marcellus Conney, 13 McDonnell St,

Amsterdam, N.Y. 12010 Filed Aug. 31, 1964, Ser. No. 393,132

11 Claims. (Cl. 333-81) This invention relates to step attenuator arrangements. More particularly, it relates to an improved step attentuator arrangement of the type in which any of an array of coaxially disposed attenuators may be selectively engaged.

T-hearrangement described .is equally applicable for use as a coaxialdevice other than an attenuator such as, for

example, a coaxial 'filter. I

Where high frequency and microwave signals are employed, step attenuators have been designed so as to enl'able uniform attenuation over a wide band of frequencies by a chosen amount. Thus, a step attenuator may comprise a plurality of individual attenuators each being con- I stru'ctedso astoeffect a given quantity of attenuation.

The particular amount of attenuation is accomplished by inserting the proper individual attenuator into the circuit.

A typical construction of an individual coaxial attenuator comprises a resistive network within a coaxial structure. The known step attenuator arrangements have employedv a coaxial array of such individual attenuators wherein the respective attenuatorseach have a different attenuation characteristic and means for selectively inserting any of the individual attenuators into the circuit.

A common form of selective insertion means has been of the type in which a centrally axially disposed control shaft is first pulled to disengage an attenuator in circuit,

. its individual attenuators into circuit and wherein required length of movement is substantially decreased.

Inknown pull-tur-n-push step attenuator arrangements, the connectors for engaging the opposition ends of the selected attenuator may begin to make contact with the attenuator prior to the attaining by the attenuator of the precise position for insertion into the circuit. This results in an undesirable increased friction surface and consequent connector wear with resulting shortened life and decreased reliability.

It is, therefore, another object of this invention to provide a coaxial step attenuator in accordance with the preceding object which is characterized by increased life and reliability.

Because of the operational complexity attendant upon the pu'll-turn-push operation of known step attenuators,

- there often results unreliable electrical contact once the 7 selected attenuator has been purportedly inserted into cir cuit by the push motion.

It is accordingly, a further object of this invention to provide a coaxial step attenuator in accordance with the preceding objects in which good electrical contact is maintained with the individual attenator inserted into circuit throughout the period of its presence in the circuit.

In accordance with the invention, there is provided a step attenuator comprising an assembly of attenuator pads and a pair of connectors. Means are included for mounting the connectors in spaced registration for selectively engaging the terminals of the attenuator pads. There are further provided means for rotating the assembly and means responsive to such rotation for causing the connectors toeifect disengagement from the attenuator pad in the circuit at the moment rotation is initiated and, upon completion of the appropriate rotary motion, to effect engagement with a newly-selected attenuator pad.

For a better understanding of the invention together with other and further objects thereof, reference is made to the following description taken in connection with the following drawings and its scope will be pointed out in the appended claims.

In the drawings, FIG. 1 is a view of an illustrative embodimentof a step attenuator constructed in accordance with the principles of the invention.

FIG. 2 is a view taken along lines 22 of FIG. 1 looking in the direction of the arrows.

FIG. 3 is an end View of the mating surface of a connector assembly of the step attenuator of the invention.

FIG. 4 is a cross-sectional view showing a terminal end of an individual attenuator pad and a connector assembly in electrical contacted position; and

FIG. 5 is a view similar to that of FIG. 4 but showing the terminal end of an individual attenuator pad and the connector assembly in non-contacted position.

Since the step attenuator of the figures is essentially a symmetrical structure, for convenience, corresponding elements are designated with the same numeral, one of the elements being designated with the prime notation.

Referring now to the figures, the illustrative embodiment of the coaxial step attenuator of the invention shown therein comprises a plurality of attenuator units or pads 10, disposed equispaced from each other in a substantially circular array. Each of pads 10 is chosen to have a unique db attenuation value or characteristic. Thus, in the embodiment shown, as an example, the individual attenuator pads may have values of 5, 10, 15, 20, 25 and 30 db attenuation values respectively. The step attenuator shown in the figures comprises six attenuator pads. It is to be realized, however, that such number has been chosen for convenience of explanation and that any number of pads may be designed into the assembly.

The connector portion of an attenuator pad may suitably comprise, as shown in FIGS. 4, 5, an inner conductor 12 which may suitably comprise beryllium copper, an insulating jacket 14 which may suitably comprise a dielectric such as Teflon and an outer cylindrical jacket 16 which may comprise a material such as brass, jacket 16 being the outer conductor, i.e., the shielded portion of the attenuator pad and which is normally grounded to constitute the return terminal of the attenuator pad. At the terminal ends 11 and 11 of each attenuator pad 10, there are provided attenuator connectors 13 and 13' which respectively mate with the connector assemblies 20 and 20' as is further explained hereinbelow.

To maintain the attenuator pads in equispaced position in a circular array, there is provided a turrent assembly 18. Turret assembly 18 comprises like turret plates 19 and 19', each of the latter structures comprising a circular plate consisting of a strong rigid material such as a strong metal or a strong semi-rigid plastic material such as nylon. Provided at the periphery of each plate are equally angularly spaced cut out portions such as 21 shown in FIG. 2. The number of cut-out portions in each plate equals the number of attenuator pads in the array. Since the attenuator pads are essentially of circular cross section,

, the cut-out portions are chosen to have an approximately semi-circular configuration to snugly accommodate the periphery of an attenuator pad. However, the exact configuration is not material and any other suitable configuration may be used.

In assembling the step attenuator, the end plates 19 and 19 are disposed in spaced parallel arrangement with their corresponding cut out portions in registration, the spacing being such as to receive the opposite ends of each attenuator pad in the registered cut-out portions 21. Plates 19 and 19' are connected to the opposite ends respectively of a turret post by suitable means (not shown) which is centrally positioned with respect to plates 19 and 19', the latter carrying the symmetrical-1y arranged array of attenuator pads 10. Attenuator pads 10 may be retained in turret assembly 18 by a pair of spring clips which substantially completely engage the circumference of the attenuator pad array. Alternatively, when a suitable plastic such as nylon is employed for plates 19 and 19, the pads may be retained by pressing each into respective cutouts utilizing the flexibility of the plastic to receive and retain the pad. Both of the foregoing arrangements permit easy removal and replacement of any of the individual attenuator pads.

Positioned respectively at the outer surfaces of plates 19 and 19' are a pair of like roller assemblies 26 and 26'. A roller assembly such as assembly 26 comprises a hub 28 from which there extend radially rollers 30, rollers 30 being disposed in equispaced arrangement and being aflixed to hub 28 by shoulder bolts 32. Rollers 30 are suitably of cylindrical configuration and are chosen to have a diameter such that each can be readily positioned with some clearance between the ends 11 of two adjacent attenuator pads 10. Rollers 30 are provided in an amount equal to the number of attenuator pads and hub 28 is of circular or polygonal configuration to accommodate said rollers.

Two like connector assemblies and 20' are provided. A connector assembly comprises a connector which includes a flanged metallic cylindrical housing 34 which serves as the outer conductor. Two ramps 38 and 40 are machined at an appropriate angle and at an appropriate angular displacement on the connector flange 36. Ramps 38 and 40 are disposed on the inner surface of flange'36 such that when a connector assembly such as assembly 20 is mated with connector 13 of an attenuator pad 10, the adjacent rollers 30 on either side of the attenuator pad are both at the bottom of their adjacent ramps.

To enable the positioning of the connector assemblies, there are provided two like end plates 42 and 42. Plates 42 and 42 are spaced sufficient like respective distances from the ends 11 and 11 of attenuator pads 10 whereby suflicient portions of connector assemblies 20 and 20' may be accommodated so as to enable the use of like pressure springs 44 and 44 for loading each of the connector assemblies 20 and 20 respectively. The connector assemblies are inserted through bearing flanges 46 and 46'.

A shaft 48 extends from the outer side of end plate 42 through end plate 42', hub 28', turretplate 19, turret post 17, turret plate 19, hub 28 and end plate 42, the end 49 of shaft 48 terminating in a knob 52, the end 50 of shaft 48 being affixed by means of C washers or other suitable means. End plates 42 and 42 which are suitably chosen to be of square configuration, are held in place by four rods 54, 56, 58 and 60, the rods extending through respective registered openings at the four corners of end plates 42 and 42' and being 'aflfixed thereto. It is seen in FIG. 2 that flange 36 is provided with a notch 37 therein for receiving rod 56. Accordingly, rod 56 also serves the purpose of maintaining connector assemblies 20 and 20 in the proper axial position. Hubs 28 and 28 are suitably mechanically connected to shaft 48 so as to be rotatable therewith by means not shown. Such connection may be by mechanical connection to flats on the shaft and set screws in the hub, or by other arrangements well known in the art.

In FIGS. 3 and 4, there is seen a ferrule 62 which is provided in each connector assembly and, as will be further explained functions to maintain firm seating of the connection between a connector assembly and an attenuator pad.

In a connector assembly 20, the outer conductor 34 including flange 36 and ramps 38 and 40'm ay suitably consist of a metal such as brass or steel. Ferrule 62 may suitably consist of a metal such as'beryllium copper and the insulation 66 surrounding the beryllium copper inner conductor 68 may be of Teflon. I

In considering the operation of the step attenuator depicted in the figures, it is, of course, realized that'the step attenuator is a structure which is symmetrical about its central axis and, consequently, the mechanical action which occurs during its operation is identical at both ends.

In operation, if it is assumed that the situation exists wherein one of attenuator pads 10 is connected in circuit with the cable and it is'desired to change attenuator pads, when knob 52 is first turned, roller assembly 26 is also turned whereby the pair of rollers 30. on either side of the roller ramps 38 and 40 of the connector assembly are caused to press against these roller ramps and thereby force the connector assembly to be moved out of contact with the connector 13 of the connected attenuator pad, the force being applied to pressure spring 44.

As knob 52 is further turned, rollers 30 engage the sides of the attenuator pad connectors 13 thereby causing the turret assembly 18 including the attenuator pads retained therein to rotate. During the turning of turret assembly 18, connector assemblies 20 and 20' remain out of electrical connection first, because of the contact between the rollers and the roller ramps; secondly, because of the contact between the rollers 30 and the flat inner surface 64 of flange 36, and; thirdly, because of the contact between the attenuator connectors and the flat inner surface 64 of flange 36.

From the foregoing, it is appreciated that the connector assemblies, once disengaged from contact with an attenuator pad, can only again electrically engage an attenuator pad when the attenuator connectors are properly positioned between the pair of roller ramps at each end and respective pairs of adjacent rollers are positioned symmetrically on the ramps.

Since the latter conditions cannot occur while turret I assembly 18 is being turned as torque applied to shaft 48 prevents the rollers from being centered between =adjacent attenuator connectors, the connector assemblies remain disengaged until the desired attenuator pad is in position and shaft torque is removed, i.e., knob 52 is released.

Once the desired attenuator pad is in the proper position between the roller ramps, the spring tensioning action provided by pressure springs 44 and 44 causes connector assemblies 20 and 20' to be urged into contact with attenuator connectors 13 and 13. At this point, to insure proper seating, the roller ramps aid in pushing the rollers into their correct positions as the connector assemblies are urged forward by pressure springs 44 and 44.

Thus, attenuator connectors 13 and 13' and connector assemblies 20 and 20' respectively firmly engage, the proper positioning being assured by the roller ramps and by the ferrule 62 which seats in the recesses of attenuator connectors 13. The spring tension provided by springs 44 and 44' maintains firm electrical contact until knob 52 is again turned.

From the foregoing, it is seen that with the step attenuator constructed in accordance with the principles of the invention, there is made possible the selection of an attenuator pad by a slight twist of knob 52. Thus, a minimal rotary motion, i.e., as little as 10 movement of knob 52, causes disengagement of the connector assemblies from an attenuator pad and provides clearance for the connector assemblies. The presence of the pressure springs, the ferrules 62 and the spring fingers of the inner conductor 68 insures good electrical contact both for the inner. and outer conductors, The small area of connector sliding friction required in the operation of the step attenuator provides long life with its consequent longer lived reliability.

It is understood that knob 52 may be manually turned or may be motor-driven in an automatically controlled arrangement.

While there has been described what is considered to be a preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, aimed in the ap pended claims to cover all such changes and modifications as fall within the spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A step attenuator comprising a pair of like plates disposed in spaced parallel arrangement, each of said plates having a like given plurality of equispaced cut-out portions in the peripheries thereof, said respective cut-out portions of said plates being in registration, a plurality of attenuator pads equal in number to said given plurality, each of said pads being received near their opposite terminal ends in respective pairs of registered cut-out portions to provide a longitudinally oriented symmetrically circular array of individual attenuator pads and having end portions extending beyond said plates, a shaft centrally longitudinally disposed within said array, the opposite end portions of said shaft extending beyond said plates, means mounted on said end portions of said shaft and mechanically connected to said shaft to be rotatable therewith and disposed to encounter said terminal end portions of said attenuator pads whereby the rotation of said shaft and said last named means causes said array to be correspondingly rotated, a pair of connectors, means for mounting said connectors in spaced registration for selectively engaging the terminals of said attenuator pads and for permitting movement of said attenuator connectors reciprocally in respective opposite directions parallel to the longitudinal axis of said array, and means responsive to said rotation for causing said connectors to be moved in said direction to effect the engagement and disengagement of said connectors with a selected attenuator pad.

2. A step attenuator comprising a pair of first like plates disposed in spaced parallel arrangement, each of said first plates having a like given plurality of equispaced cut-out portions in the peripheries thereof, said respective cut-out portions being in registration, a plurality of attenuator pads equal in number to said given plurality, each of said pads being received near their opposite terminal ends in respective registered cut-out portions to provide a longitudinally oriented symmetrical circular array of individual attenuator pads and having end portions extending beyond said first plates, a shaft concentrically longitudinally disposed within said array and having portions extending through each of said first plates, a pair of like structures mechanically connected to said extending portions to be rotatable therewith and disposed to bear against said attenuator end portions upon its rotation to cause said array to be rotated, a second pair of like plates in parallel arrangement with said first plates, said second plates being respectively spaced from said structures, means for main taining said second plates in fixed position, a pair of connectors extending through said registered areas of second plates toward said array to dispose said connectors for selectively engaging the terminals of said attenuator pads, a pair of first spring tensioning means operative to cause reciprocal movement of said connectors in a direction parallel to the longitudinal axis of said array, and means associated with said connectors and responsive to said rotation alone for causing said connectors to be moved in said direction to effect the engagement and disengagement of said connectors with a selected attenuator pad.

3. A step attenuator as defined in claim 2 wherein each of said structure comprises a central hub having said given plurality of equispaiced rollers radially extending therefrom, said rollers having a diametric width to permit them to be freely received between adjacent attenuator pad end portions and being disposed substantially coplanar with said end portions.

4. A step attenuator as defined in claim 3 wherein said connectors terminate in respective flanged portions, the periphery of a terminal surface .of a flanged portion having a pair of ramps thereon, said ramps being disposed to receive adjacent rollers when said connectors are in engagement with an attenuator pad.

5. A step attenuator as defined in claim 4 wherein said shaft extends beyond each of said second plates.

6. A step attenuator as defined in claim 5 and further including means for maintaining said attenuator pads in said circular array.

7. A step attenuator as defined in claim 6 and further including a hollow post extending between said first plates to which said first plates are afiixed, said shaft passing through said post.

8. In combination, :an assembly of a plurality of angularly spaced circuit components, a pair of connectors, means for mounting said connectors in spaced registration for selectively engaging the respective terminals of said components, means associated with said assembly and independently rotatable with respective thereto for causing, the displacement of said connectors from said terminals and the thereafter rotation of said assembly to elfect the engagement of said connectors with discrete selected ones of said circuit components upon the rotation of said rotatable means only the angular spacing between two adjacent ones of said components, and means for rotating said rotatable means.

9. A step attenuator comprising an arcuate array of attenuator pads, a pair of connectors, means for mounting said connectors in spaced registration for selectively engaging the terminals of said attenuator pads for permitting movement of said conductors reciprocally in respective opposite directions parallel to the axis of said array, means associated with said array and independently rotatable with respect thereto for causing, the displacement of said connectors from said terminals and the thereafter rotation of said array to effect the engagement of said connectors with discrete selected ones .of said atteuator pads upon the rotation of said rotatable means only the angular spacing between two adjacent ones of said pads, and means for rotating said rotatable means.

10. A step attenuator comprising a longitudinally oriented symmetrically circular array of a plurality of individual attenuator pads, a pair of connectors, means for mounting said connectors in spaced registration for selectively engaging the terminals of said attenuator pads and for permitting movement of said connectors reciprocally in respective opposite directions parallel to the longitudinal axis of said array, means associated with said array and independently rotatable with respect thereto for causing the displacement of said connectors from said terminals and the thereafter rotation of said array to effect the engagement of said connectors with discrete selected ones of said attenuator pads upon the rotation of said rotatable means the angular distance between two adjacent ones of said pads, and means for rotating said rotatable means.

11. A step attenuator comprising a longitudinally oriented symmetrical circular array of a plurality of in dividual attenuator pads, a pair of connectors, means for mounting said connectors in spaced registration for selectively engaging the terminals of said attenuator pads and 7 8 for permitting movement of said connectors reciprocally References Cited by the Examiner in respective opposite directions panallel to the longituv UNITED STATES PATENTS dinal axis of said array, means associated with said array v p and independently rotatable with respect thereto for caus- 3,197,334 10/1963 Harges 333*81 ing, the displacement of said connectors from said termi- 5 31219953 11/1965 Schwartz 333 '81 nals and the thereafter rotation of said array to effect the I vFOREIGN PATENTS engagement of said connectors with discrete selected ones of said attenuator pads upon the rotation of said rotatable means the angular distance between two adjacent ones of said pads, and shaft means mechanically coupled to'said I rotatable means and extending axially through said array R. F. HUNT, Assistant Examiner. for rotating said rotatable means.

797,756 7/1958 GreatBritain.

HERMAN KARL SAALBACH, Primary Examiner. 

8. IN COMBINATION, AN ASSEMBLY OF A PLURALITY OF ANGULARLY SPACED CIRCUIT COMPONENTS, A PAIR OF CONNECTORS, MEANS FOR MOUNTING SAID CONNECTORS IN SPACED REGISTRATION FOR SELECTIVELY ENGAGING THE RESPECTIVE TERMINALS OF SAID COMPONENTS, MEANS ASSOCIATED WITH SAID ASSEMBLY AND INDEPENDENTLY ROTATABLE WITH RESPECT THERETO FOR CAUSING, THE DISPLACEMENT OF SAID CONNECTORS FROM SAID TERMINALS AND THE THEREAFTER ROTATION OF SAID ASSEMBLY TO EFFECT THE ENGAGEMENT OF SAID CONNECTORS WITH DISCRETE SELECTED ONES OF SAID CIRCUIT COMPONENTS UPON THE ROTATION OF SAID ROTATABLE MEANS ONLY THE ANGULAR SPACING BETWEEN TWO ADJACENT ONES OF SAID COMPONENTS, AND MEANS FOR ROTATING SAID ROTATABLE MEANS. 